FI63004B - PROCEDURE FOR THE PURPOSE OF PELLETERING AV PARTIKULAERT MAENGMATERIAL - Google Patents

Description

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National Board of Patents and Registration (44) Nlhttvikj | p * non) · ItUMtJulkftkwn prm. - 10 years

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(32) (33) (31) requested muoUmim — 4 «gtri priortt * 2h. 06.77 USA (US) 809595 (71) Owens-Corning Fiberglas Corporation, Fiberglas Tower, Toledo, Ohio 1 + 3659 »USA (US) (72) Stephen Seng, Frazeysburg, Ohio, USA (US) (7 * 0 Oy Kolster Ab The present invention relates to a method and apparatus for pelletizing a particulate alloy, wherein the particulate alloy is fed to a rotating surface which is kept rotating and fed with a liquid. , wherein the physical property of the surface alloy is measured and that the ratio of liquid to alloy is changed depending on the change in the measured physical property.

It has been found that it is advantageous to collect the combustion products or hot gases from the molten glass in the glass melting furnace or unit and to conduct them so that heat exchange takes place with the filler fed to the melting furnace. In this way, the filling batch can be preheated to elevated temperatures in order to save considerable amounts of energy that are needed later to melt the filling batch. Otherwise, the exhaust gases are simply released to the outside air, in many cases a lot of heat and energy is lost.

2 63004 The thermoplastic alloying agent is preferably in the form of pellets in the heat exchange chamber through which the hot gases are passed. However, it has been found that the grain size must be substantially uniform. Otherwise, granules of different sizes tend to accumulate and greatly impede the flow of gas past the granules in the chamber. In addition, it has been found that in addition to the uniformity of the granules, the grain size is relevant. If the granules are too small, the flow of hot gases will be blocked too much. If the granules are too large, the ratio between their surface and weight decreases accordingly, thereby reducing the heat transferred to them. In addition, moisture remaining in the larger granules can turn into steam and cause the granules to explode. In particular, it has been found that the nominal diameter of the granules of 12.7 mm is the limit, with a diameter variation of 9.5 to 15.9 mm, for achieving the maximum heat transfer from the hot exhaust gases to the granules.

The granules of the thermosetting alloy are mainly prepared in a modified, commercially available granulating machine. The ingredients of the filling batch are mixed together and then fed to a granulating machine. When a batch of material is fed to a granulating machine, its ingredients tend to differ so that the batch actually fed to the machine varies, although the final granules produced, which are fed to the melting furnace or unit, become flattened so that short variations are not essential. However, short variations in the components of the fill batch tend to adversely affect the granulating ability of the fill batch and the size of the granules made, but other factors do not change. The speed at which the batch is fed to the granulating machine will also vary and thus also adversely affect the granulation formation and grain size. Liquid, and in particular water, is also fed to the granulating machine near the point where the filling batch is fed. When the ingredients or amount of a batch varies, granules of different sizes result when the amount of water is kept constant. However, it has been found that the amount of water or the ratio between the filling batch and water will adversely affect the grain size, as a higher amount of water will result in larger granules and a lower amount of water will result in smaller granules, at least in most cases.

In addition, it has been found that measuring the physical property of the filler batch received by the granulating machine during granule production can result in a grain size prediction so that the amount of water or the batch to water ratio can be changed to avoid adverse grain size reduction or decrease before this occurs. More specifically, the depth of the alloy in the granulating machine in certain parts thereof can be measured and the water flow can be changed according to the measurement. The increasing depth of the alloy particles means a higher water content because the water causes the particles to adhere more together and thus accumulate higher. Thus, the amount of water fed to the granulating machine is reduced when the sensor indicates that the depth of the filling batch has reached a predetermined value. Excess water would otherwise give less granules with a larger diameter if the amount of water were not reduced. If there is too little water, at the same time the depth of the particles in the filling batch decreases, thus increasing the amount of water. A lower amount of water would otherwise result in the individual final granules becoming smaller, but a larger amount being obtained.

The object of the invention is to provide a method and an apparatus for producing pellets of uniform size by measuring a physical property of the admixture from which the granules are made in a granulating machine.

The features of the method and device according to the invention appear from the appended claims.

Other objects and advantages of the invention will become apparent from the following detailed description of the preferred embodiments thereof, with reference to the accompanying drawings, in which: Figure 1 shows a schematic, vertical projection view of an apparatus shown for treating a thermoplastic alloy; Fig. 2 shows a front vertical projection view of the granulating device of Fig. 1; 4 63004 Fig. 3 shows a plan view of the device of Fig. 2; Fig. 4 shows a schematic view on a larger scale of a part of the granulating device; and Fig. 5 shows a schematic view of control means for measuring the dopant in the granulating device and for controlling the flow of water to the device.

According to Figure 1, the particulate, thermoplastic composition is conveyed to a feed pocket 10 and fed to a granulating device 12. The particulate composition is formed into granules (pellets) which are discharged into a tray 14 with openings 16 (Figures 2 and 3) through which smaller or crushed granules. The granules are fed to a horizontal conveyor 1Θ and conveyed by means of a vertical conveyor 20 to the upper end of the heat exchange pocket 22 forming the heat exchange chamber. The granules then pass down through a feed tube 24 to a feeder 26 which feeds the granules to a melting unit or furnace 28.

From the furnace 28, hot exhaust gases or combustion products are led through the chimney 30 to the bottom of the pocket 22. The exhaust gases are then sucked through the pocket 22 by the fan 32 and are allowed to exit. The heat exchanger pocket 22 is so large that the exhaust gases passing through it have a low velocity and do not carry the granules out through the fan 32. A significant portion of the heat from the exhaust gases is transferred to the granules in the heat exchange pocket 22, so that the granules have an elevated temperature when they enter the furnace 28. This achieves a much higher degree of efficiency for the furnace 28.

The uniform size of the granules themselves is very important. If the grain size varies too much, the granules tend to accumulate in the pocket 22 and significantly restrict the flow of exhaust gases through the pocket. However, if the granules have a sufficiently uniform size, there is sufficient cavity between them so that the exhaust gases can pass through without becoming too obstructed. The nominal diameter of the granules is also important because too small granules prevent the flow of exhaust gases too much. If, on the other hand, the granules are too large, then their surface-to-weight ratio is lower and the heat transfer to them is lower. In addition, moisture tends to remain in large granules, causing moisture to explode when the exhaust gases convert it to steam. More specifically, it has been found that e.g. granules with a nominal diameter of 12.7 mm, with a variation in the range of 9.5 to 15.9 mm, form the limit within which the maximum heat transfer from the exhaust gases to the granules in the heat exchange pocket 22 is achieved.

The granulating device 12 is intended to form particulate alloying material into pellets with a nominal diameter of 12.7 mm. Unfortunately, the components of the mixture to be fed to the granulating device 12 and in particular to the feed pocket 10 tend to differ during transport. Such a separation is not dangerous for the use of the furnace 2Θ, since the components of the low-fed granules level off over a period of time, but short variations in the components of the mixture adversely affect the grain-forming ability of the mixture. Variations in the ingredients of the alloy fed to the granulator 12 result in a change in grain size, while other factors are considered unchanged. The rate at which the fill batch is fed to the granulator will also vary and change the granulation capacity and grain size when other factors do not change.

Liquid, and especially water, is fed to the granulator, and it has been found that the amount of water or the ratio of water to admixture adversely affects the grain size. Increasing the amount of water or increasing the ratio of water to admixture results in the formation of larger granules, while a smaller amount of water results in smaller granules, at least for most admixtures. According to the invention, it has also been found that it is possible to measure certain physical properties of the dopant in the granulating device 12 to adjust the water flow or the ratio of water to dopant to keep the grain size in the desired range. More specifically, the depth of the granules formed in certain parts of the alloying agent or granulating device can be measured, after which the water flow is adjusted accordingly. The greater depth of the particles in the alloy from which the granules are formed indicates that the particles have a greater tendency to stick together, thereby increasing their depth. This occurs when the amount of water or the ratio of water to admixture is increased. As the depth increases, the amount of water fed to the granulator is reduced, as a consistently excessive amount of water would otherwise lead to the formation of fewer but larger granules. As the depth of the particles is smaller, they also have a lower tendency for the 63004 to stick together, indicating that the water content is reduced and that the grain size is thus reduced. To prevent this, the amount of water is then increased.

According to Figures 2-4, the granulating device 12 comprises a movable surface 34, which in this case in particular is formed by a rotatable member or plate. However, the moving surface may also have another shape, for making granules. The plate 34 is rotatably supported by a bearing housing 36 (Fig. 1) pivotally mounted on arms 3Θ mounted on a shaft 40 mounted on a base 42. The plate 34 is moved or rotated by a suitable motor 44. The rotatable member 34 is surrounded by an annular wall 46 over which the granules roll down to the hopper 47 of the trough 14 when they are complete. The outer cleaning plow 4Θ (Figs. 2 and 3) and the inner cleaning plow 49 clean the surface of the rotating member 34.

From the feed pocket 10, the dopant is fed to the lower center of the rotating member 34 as shown in Figure 4 by a suitable feeder 50. In this case, the feeder 50 is shown with a belt conveyor 52 (Figure 2) driven by a motor 54, but other conveyors such as vibratory conveyors may be used. The feeder is intended to feed a constant amount of alloy, but in practice there is some variation in the feed rate of almost every feeder. This requires changes in the water supply, although the components of the alloy do not change. In addition, water is supplied to the lower central portion of the rotating member 34 as shown in Fig. 4 by means of a supply line 56. As the rotating member 34 rotates clockwise as shown in Figure 4, the dopant enters along substantially elliptical paths as it moves along the surface, keeping the surface at a predetermined angle relative to the horizontal, such as 45 °, as determined by the adjustment of the legs 38.

In reality, the wet alloy moves in three fairly distinct streams, or in three paths, as it is brought up along a moving surface and falls back. The outer track has cores of alloying material on which granules form. The central track has partially formed granules with diameters in the range of 6.4 to 9.5 mm, while the nominal diameter of the granules to be produced is 12.7 mm. The inner track has finished granules that roll along a narrow elliptical track until they roll over the annular wall 46.

As granules form, the particulate mixture accumulates in continuous layers to gradually increase the diameters of the partially formed granules until the desired size is reached. When moisture or water is supplied to a moving mass of particulate matter, the capillary force and mechanical force of the water against the moving surface in the agitated particulate material cause the substance to become packaged and grow into solid pieces.

The mixture of the outer flow and, to a certain extent, also of the medium flow tends to adhere more together when there is more moisture or water in the mixture, whereby the depth of the flow increases accordingly. When this depth reaches a predetermined value, the inflow of water is constricted, thus again reducing the accumulation of the alloying substance. In contrast, when the water content is higher, the dopant tends to accumulate more easily on existing cores instead of forming new cores, resulting in fewer and larger granules. In contrast, when there is less moisture or water, the tendency of the particulate alloy to accumulate decreases, resulting in more cores forming, resulting in more but smaller granules because there are more cores on which a certain amount of alloy can grow and the alloy has a lower tendency to agglomerate.

The supply of water through the line or nozzle 56 to the moving surface 34 can be adjusted by the system shown schematically in Figure 5. Accordingly, water is supplied through a first branch line 58 of the nozzle 56 which includes a manually operated valve 60. Water may also be supplied to the nozzle 56 via a second branch line 62 having a solenoid controlled valve 64 and a manually operated valve 65 for adjustment. For both line 58 and line 62, water can be supplied through a suitable supply line 66. The flow of water through line 58 to nozzle 56 is arranged to be less than the amount required to produce granules of the desired size in granulator 12. However, when valve 64 is open, the flow of water through lines 58 and 62 is greater than the amount required to make granules of desired size. to manufacture.

63004

As an example, when a typical dopant is fed to the granulating device 12 at a predetermined flow rate of 907 kg / h, the required water supply may be, for example, 151 l / h for the production of granules having a certain nominal diameter. However, for short variations in the ingredients of the alloy, the amount of water may need to be changed from perhaps 132 to 170 to maintain a grain size of 1 / h relatively constant. In this case, the water flow through the first branch line 58 can be adjusted to 114 l / h, which is below the required minimum value. The water supply through the second branch line 62 can then be adjusted to 76 1 / h. In this case, the common flow through the two lines 58 and 62 is 190 l / h, which exceeds the required maximum amount of water. Thus, the flow of liquid through line 58 is periodically supplemented with flow through line 62 to obtain granules having the desired nominal diameter.

The control of the water via lines 58 and 62 is accomplished by a suitable sensor that measures the physical property of the particulate mixture on surface 34. The meter can measure water content as described above and can do so by measuring the depth of their cores or partially formed granules. which flow in the outer or middle flows on the surface 34. In the particular example shown, the solenoid valve 64 is controlled by a time clock 68 which, when activated, supplies current to the solenoid of the valve 64 via the clock contacts for a predetermined period of time, e.g. 4 seconds. The watch, in turn, receives power through the power switch 70. The switch 70 has an actuating pin 72 connected to a stem 74 carrying a sensor or oar 76. The stem 74 in turn carries a pivotable top bar 7B connected to a vertical body 80 on one side of the granulator wall 46. The spring 82 normally holds the arm 74 against the pin 72 to keep the power switch 70 off.

The airo 76 is positioned near the annular wall 46 above the upper outer portion of the surface 34 of the granulator. It is preferably in a position where it determines the depth of the cores in the outer path of the alloy on the moving surface 34, but it can also measure the depth of the partially formed granules. When the depth of the alloying agent, i.e. either the cores or pellets, reaches a predetermined value or level, the agent comes into contact with the oar 76 and moves it counterclockwise as seen in Figure 5. The alloying agent reaches a predetermined depth as the water content increases, as described above. and causes the substance to adhere and grow. Thus, when this situation arises, it is desirable to reduce the amount of water in the filling batch or to reduce the ratio of water to the filling batch. To this end, the paddle 76, when actuated, pulls the action pin 72 of the power switch 70 outward to engage the power switch and supply power to the clock 6Θ for a predetermined period of time. When the clock receives power, it closes the valve 64, with the result that only water from line 5Θ is supplied to the nozzle 56. Each time the oar 76 is moved, it resets the clock 66 so that the valve 64 remains closed until the oar is no longer in contact. with the dopant for a period longer than that set for the clock. With this arrangement, the water content in the filling batches can be kept substantially constant, so that the desired nominal size of the granules is obtained.

If desired, a sensor or oar can be used to control the flow of dopant provided by the feeder 50. In the arrangement shown, the motor 54 may be a motor having two speeds for pulling the belt 52 at different speeds. If vibratory conveyors are used, the oscillation speed can be adjusted for the same purpose. Thus, instead of increasing the flow of water, the supply of the alloying agent can be reduced and vice versa.

Various sensors can also be used instead of Oero. The depth of the granules can be measured, for example, with a photocell. Ultrasonic waves or microwaves can also be used for this purpose. In addition, the measuring device can directly measure the water content of the particulate alloy, e.g. by means of infrared rays.

Various modifications of the described embodiments of the invention will be apparent to those skilled in the art, and these may, of course, be made without departing from the spirit of the invention if they are within the scope of the appended claims.

Claims (9)

A method for pelletizing particulate matter, in which method the particulate material is applied to a rotatable surface (34) which is poured in rotation and liquid is applied to the surface to form the material into pellets, a physical property of the material p4 surface. is sensed and the relationship between the liquid and the feedstock is changed depending on the change of the sensed physical property, characterized in that as the physical property of the feedstock, the depth of the feedstock is sensed on a predetermined portion of the moving surface. 2. A method according to claim 1, characterized in that the ratio of the liquid to the feedstock is changed by supply of liquid depending on the sensed depth of the feedstock. A method according to claim 1 or 2, in which the mixing material is applied to a lower portion of a sloping, rotating surface (34) and the liquid is applied to this surface as the mixing material, the mixing material and the grains being caused to move along the surface and then falling down of their own. weight, in that the material and the grains move mainly in elliptical paths, characterized in that the sensing of the depth of the material is carried out in an upper part of the inclined, rotating surface (34). 4. A device for pelletizing particulate matter in the process of the claims 1 to 3, comprising a device forming a rotatable surface (34), a device (44) for shaking the surface in rotation, a device (50). ) for supplying the particulate material to a portion of the surface, a device (56) for supplying liquid to a portion of the surface adjacent to the particulate material, a device (76) for sensing a physical property of the amount material on the surface (34) and a device (68, 70) for changing the ratio of liquid to particulate matter, depending on the sensed physical property, characterized in that the sensing device (76) comprises a predetermined distance across the rotatable surface (34). disposed movable disc-shaped means arranged to sense the depth of the amount of material p in a predetermined portion of the rotatable surface, and